Google Scholar is here! This new application of Google's popular (nay, essential?) Web indexing and ranking strategy enables the user "to search specifically for scholarly literature, including peer-reviewed papers, theses, books, preprints, abstracts and technical reports from all broad areas of research."
Relevance ranking in Google Scholar incorporates citation frequency data, a la the Institute for Scientific Information's Web of Science product. Also using that citation data, article citations found in Google Scholar incorporate a convenient link to other articles which have cited it.